Preparation of thermoset resins



Patented se g 195 x :7

NIT-E QS A ES PATENT OFFICE H 2,609,357 f "1 1 PREPARATION OF THERMOSET Resins Joseph E. Koroly, Philadelphia, Pa., assignor to I .-Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware I v N Drawing.

Application November 13, 1950,

Serial N 0. 195,459

19 Claims.

This invention relates tothe preparation of new thermoset resins. Itrelates to a method of making such resins and to the resins per se which are new compositions of matter having particular advantages when employed as castings, ad-

hesives, surface-coatings, foamed materials and as potting compounds for electrical assemblies.

These resins are' madeby chemically reacting, under the influence of heat, a polycarboxylie acid,which contains more than two carboxyl groups, with a particular -'kind of epoxy ether; namely, on'ehaying the general formula: iii

in which R isLth e alkylene radical of a glycol, HOR--OH, such as ethylene glycol, or the radical of a polyalhylene glycol,

such as diethyleilei'fglycol. One big advantage of preparing castiresins 'by' this process is that no significant amounts" of. gaseous by-products fundamentally from the latter by virtue of being thermoset. I

The epoxy'fethers which react by the process of this invention 'a're'tho'se which have been described by W. D. Niederhauser in his Letters Patent No. 2,543,419 which issued February 27, 1951, entitled (Polycyclic .Di-Epoxy Ethers." These ethers are actually di-epoxides'. of glycol bis-exodihydrodicyclopentadienyl ethers having the general formula given above in which R is a mem;

ber of the class consisting of (a) alkylene-groups;'-.

containing 1 to 12 carbon atoms and (11) groups of the general formula (R'O)XR' in which R is an alkylene group of 2 to 4 carbon atoms and a: is an integer, having a value of 1 to 8 inclusive."

In the process of this invention reaction takes 2;. place at the two terminal epoxygroups and the remainder of the molecule including the group represented by R remains intact.v Therefore, the group represented by R can'v'ary within the limits set forth abovewithout adversely -i affecting the course of:. the.reaction.' Thus, the process-of this invention is applicablefto thereaction' of polycarboxylic'a'cid with the diepoxidesof the ethers of dicyclopentadienej'and glycol's', which glycolsaretypifiedaby the following:' Ethylene glycol, diethylenegglycol, the isomeric butylene' glycols, hexamethylene glycol and its branche'd chained isomers such "as 1,2-dihydroxyhexane,

octylene glycols suchza's"::1,2.-dihydroxyoctane or 5 1,8-dihydro'xyoctane, trlethylene glycol, tetrapropylene'glycols, dibutyl'ene glycols, hexabutyl ene glycols, and octaethylene glycols.

wThe polycarboxylicacids which react by the process of this invention are those which contain three ormore carboxyl groups. Typical of such acids are citric,tricarballylic, hemimellitic;

trimellitic, and pyromelliticacids. Of greater in terest, however, than these acids'are thos'zghalfester-polycarboxylic acids-made by reacting di- 5 carboxylic acids or their anhydrides with-polyhydric alcohols such asglycerol, pentaerythritol,

dipenta'erythritol, 'sorbitol, 'mannitol, and the like whereby the half=estershalf=acid is formed. These ester-acids are-readily prepared by reacting one mole. of the polyhyd'ric alcohol with that number of moles of dibasic acid or anhydride' which isequal to the number ofhydroxyl groups inthe alcohol. Thusgfo'r example, in preparing such half-ester-acid's from glycerol, one mole of lycerol is esterified with three mole's'-of"a"dicarboxylic acid such as phthalic acid-or preferably with three moles of an acid anhydride such as phthalic anhydride. Similarly, in the case of pentaerythritol four moles of a di 40 carboxylic acid or its anhydride are reacted with onemole of the tetrahydric alcohol. Furthermore, mixed ester-acidswhave been reacted with theiepoxyfethers tov give resins of outstanding properties asjfor instance, the ester-acid made by v reactin gj one i mole. of pentaerythritol with three moles; of phth'alic anhydride and one mole of maleic anhydride'. This particular ester-acid has theayerageformula I CHzOOC-CI-l=CH-COOH Half-ster-acids are operable which are made from any mixture of dibasic acids set forth herein so long as the total number of moles of the acids reacted with one mole of the polyhydric alcohol formula Thus, it is preferred is equal to the number of hydroxyl groups in the alcohol.

The half-ester-acids made from such alcohols as glycerol or pentaerythritol and saturated, aliphatic, dicarboxylic acids having the general I I-IOOC; (CHzM-COOH in which :0 is an integer of value 2 to 8 also react with the bis-epoxy others in the same manner to give resins. These resins, however, differ in physical properties, as might be expected, from those resins made with the ester acids from the same alcohol and maleic or phthalic anhydrides. Examples of such reactants include the half-ester-acids made from glycerol, pentaerythritol, dipentaerythritol, mannitol or sorbitol and succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids. The above-described polycarboxylic acids all react by the process of this invention toform' resinous products, but it also isgtobe understood. thatother carboxylic acids which contain three: or lmore carboxyl groups, such as polymeric acids, as well as mixtures :of polycarboxylic acids react in the same way and that the physical properties of the resultant products vary from resinouscross-linked semi-fluid gums to hard, tough, infusible, durable masses depending upon. th'eparticular polycarboxylic acid and the kind and'size of the group, represented byR; in theepoxy ether.

The reaction of the'polycarboxylic acid and the epoxy-ether is carried out under the influence of heat and the chemical reaction occurs more rapidly as the temperature'is raised; Temperatures from 50 C; to 250 G5 have been employed successfully but .those'from about 100 C. to about 200 C; are muchfpreferred. .At the lowest temperatures the'rateoffreaction may be objectionably slow, especially when-large quantitles of reactants are involved. At the highest temperatures objectionable discoloration may take place. When the process of this invention is usedto prepare castings, a very satisfactory procedure is to place the mixture of reactants in a mold and heat the mold at a convenient temperature until the reactants have. combined to form a self-sustainingor rigid mass and then to remove this mass from the mold and. continue the reaction or cure for example in an oven or under infra-red radiation. i ,1.

During the preparation of the products ofjthis invention it is believed thata carboxyl group reacts with an epoxy group to'v form. a, hydroxy ester in this way: i 1

that the polycarboxylic acids and the bis-epoxy ethers be reacted in such a ratio as to provide one carboxyl group for each epoxide group. since the bis-epoxy ethers contain two epoxide groups, it is evident that one mole of the bis-epoxy ether will react according to the above equation with one-half mole of a tetracarboxylic acid or that three moles of biscantly deleterious effect onthe product.

epoxy ether will react in a like manner with two moles of a tricarboxylic acid. While it is preferred to react the bis-epoxy ether and polycarboxylic acid in the above ratio, it is true, however, that additional quantities of acid can react to esterify the .hydroxylgroups shown in the product ofth'e equatiomabove. vTins/secondary reaction takes the following course:

It is to be noted that, although water is liberated by the secondary reaction, the amount of water is in reality negligible because of the fact that both the bis-epoxy ethers and polycarboxylic acids are of unusually high molecular weight. In view of the secondary reaction, the amount of acid which can react is actually that amount which provides two carboxyl groups for each epoxy group in the bis-epoxy ether. As the amount of acid is raised from the preferred ratio required by Equation 1 to that requiredby Equation 2, the physical properties ofthe products change slightly. Thus, the products are. harder but have somewhat lowered flexuralstrength, which is considered a measure'oftoughness, and lower heat-distortion, temperatures. Alterna tively, even a lower amount-oi acid can beemployed than that required by Equation 1 above. This means that an excess of the bis-epoxy ether can be employed and up to a certain point the presence ot'this excess does not exert a signifi- The fiexural strength, Barcol hardness, and heatdistortion temperature remain essentially unaffected. Therefore, the polycarboxylic acid and the bis-epoxy ether can be employed in such amounts as to provide from about 0.7 to about 2.0 carboxyl groups in the acid for each epoxy group in the bis-epoxy ether. 7

Fillers, extenders, dyes, pigments, and the like can also be added to the mixture of reactants in order to modify the product. In a similar way, plasticizers such as high-boiling monomeric esters, typified by dibutyl' phthalate and tricresyl phosphate, or epoxidized vegetable oils can be incorporated;

Catalysts have been added to the reaction mixtures of this invention in order to accelerate the formation of the resinous products. Boron triflucride and itscomplexes with others, acids, and

amines have been used as well as a large number ing, embrittling, or discoloration of the product, Butyl and cresyl diacid phosphates are the most.

satisfactory to date.

The following examples serve to illustrate how the products of this invention are prepared.

'Emample 1 One mole of the diepo'xide of the bis-exo-dihydrodicyclopentadienyl ether of diethylene glycol, having the formula and one-halrmoleoi pentaerythrityl.tetraeacid trimaleate-monophtha1ate, having the formula were mixed in a beaker and the stirred mixture was heated. This ratio provided one carboxyl group for each epoxy group in' the bis-epoxy ether. The mixture began to fuse at 75 C. and was clear and homogeneous at 125 C. At this stage the reaction mixture could easilybe poured and a sample, on cooling, changed into a solid but fusible mass. The thermoplastic mass was thenheated to 150 C. where it was held for four hours. During this period of heating the mixture gradually increased in viscosity until atthe' end it had become a hard, tough, infusible. resinous mass. This change from the thermoplastic to thethermoset condition was rapid but not abrupt. Thus, after about one-half hour the mass was gummy at 150 C.; after an hour it was a firm solid, which, however, could be dented at 150 C. by a pencilpoint While after two hours it could not be so dented. Samples of the resinous product were taken at intervals 'andtestedfor hardness after being cooled to room temperature. The'sample taken after one hour of heating 'at 150 C. had a Barcol hardness of 30-32. The sample taken aftertwohours of heating had a Barcol hardness of 36-38, while. the finalproduct had a hardnessof l. Y The physical properties of this resin are evident from the resulting data:

Flexural strength 19,500 lbs./sq.'in'.' Flexural modulus 383,000 lbs/sq. in. Compressive strength 18,300 lbs/sq. in. Tensile strength 11,400 lbs/sq. in. V Elongation at break 7% Modulus of elasticity 420,000 lbs/sq. in. Impact strength (izod) 1.3 ft..-1bs;/in. of

' -notch."

Linear coeflicient of exa .pansion 6.0xper--C. Heat distortion temp 127 C. (i fiexure,-10 mil distortion, 264

lbs/sq. in.,-

2 C. /min.)'

4.0 (60 cycles) 4.0 (10 cycles) 3.6 (10 cycles) 0.006 (60 cycles) 0.012 (10 cycles) 0.035 (10 cycles) A Example 2 Dielectric constant Power factor and one-half mole of the same acid as was used in Example 1; viz. pentaerythrityl tetra-acid tri- 6 at.'1 50 -Ci for fourihoursj. .iCooled samples taken at various intervalsv had the following Barcol values for hardness: 35-37 'after one hour; 42-44 after: two 1 hours ,and 42-43 after four hours. This product like that of Example 1 had good impact-resistance. j

. Example 3 The procedure of Example' 1 was repeated with one change; namely,'*the' use of the diepoxide of the bis-exo-dihydrodicyclopentadieny1 ether of ethylene glycol was used-in place of the ether of diethylene glycol of Example 7 Here, as in the first example, the product was a hard, clear,

tough, thermoset, resinous product having a A wide variety of polycarboxylic acids containing 3 to 6 carboxyl groups was reacted with the bis-epoxy ether employed in Example 1. The amounts of reactants in all cases was such that the number of carboxyl groups was equal to the 1 number of epoxy groups in the bis-epoxy ether.

e. v Pentaerythrityl tetra-acid maleate Dipentaerythrityl hexaacid phthal- In each casethe bis-epoxy ether and the polycarboxylic acid were mixed thoroughly, put in a shallow aluminum container, and then heated first at a temperature'of '100'C i'or onehour'and then at'150'- C. for four ho'uisfi The acids and the general characteristics f the products are here tabulated: i

Aha '1 Product Tricarballylic Barcol34-36. Very tough. Qlyceryl trlacid phthalate Barcol 30. Very tough. Glyceryl triacid maleate Barcol 30-35. Tough.

Partaerythrityl tetraacicl phthal- Barcol 35. Tough.

Barcol 3235. Tough. Very pale color.

Barcol 34-35. Excellent impact resistance.

Barcol 3035. Tough. Very .pale color.

Barcol 35-38. Tough.

Parcel-40. Very tough. Very e. Glyceryl triacid dimaleatc monophthalate. Glymlaz-yl7 triacid diphthalate monoa e m ea Pentoerythrityl tetraacid diphthalate dimaleete. v pale color.

Pentaerythrityl tetraacld mono- Barccl 36-40. Verytough.

maleate triphthalate. I Very pale color.

I Pentacrythrityl tetra'acld adipatc" Barcol 0. Toughj"'iiexible "1 eritaerythrityl tetraacid trisuc- .Pentaerylghrityl tetraacid tetrahy- 'Barcol 25. Tough. Dark color.

Pentaerythrityl tetraacid succinate.

'Barcol 37. Very tough.

Sorbityl hexaacid maleate phthal-' ate (3/1). Pentaerythrityl tetraacid trimale- Barcol 30-32. Very tough.

ate monoadipate. Adhesive. Pentaerythrityltetraacid glutarate. Barcql 0. Very tough. Ad-

hesive. Barcol 30. Brittle. Poor color.

Barcol 25-29. Brittle.

ate monophthalat droph alate.

1 I claim:

p 1. A process for preparingcross-linked, resinous products whichcomprisesreacting ata temperature Oreo" 0; 156250 of; (1) a diepoxide era glycol bis-exo-dihydrodicyclopentadienyl' ether which has the formula maleate-monophthalate was he atedto 1500.

and held there for four hours. "Again .themixture fused at C., was a clearl homcg'eneous liquid at 0., and passed from a liquid' to a. hard, tough, resinous, inf-usible mass when held .in.which R is a memberof the. class consisting a value .of 1- to. 8. inclusive,"with '(2) a polycarboxylic acid cont'aining'3 to 6 carboxyl' groups 7, fromthe class consisting of citric, tricarballylic, hemim'ellitic, trimellitic, and pyrornellitic acids and. the half ester-acids of a poly'hyd'ric alcohol from the class consisting of glycerol, pentaerythritol, dipentaerythritol,-mannito1; and:sorbital and at least one acid from the class consisting of phthalic, maleic, succinic, glutaric, adipic, suberic, azaleic, and sebacic acids, the amount of said polycarboxylic acid'being that which provides 0.7 to 2.0 carboxyl groups for each epoxy group present in said diepoxide. 7

2. A process for preparing cross-linked, resinous products which comprises reacting at a temperature of 100 C. to 200C. (1) a diepoxide of a glycol bis-exo-dihydrodicyclopentadienyl ether which has the formula a i I in which R is amember of the class consistingof (a) alkylene groups containing 1 to 12 carbon atoms and (12) groups of the general formula (R'-O) IR- in which R is analkylene group of 2 to 4 carbon atoms-and a: is an integer having a value of 1 to 8 inclusive, with 2) apolycarboxylic acid containing3 to 6 carboxyl groups from the class consisting of citric, :tricarballylic;

hemimellitic, trimellitic, and. pyromellitic acids and the half-ester-acids of a polyhydric alcohol from the class consisting of glycerol, pentaerythritol, dipentaerythritol, mannitol, and sorbitol and at least one acid from the class consisting of phthalic, maleic, succinic, glutaric, adipic, su-

beric, azaleic, and sebacic acids, the amount of said polycarboxylic acid being that which provides 0.7 to 2.0 carboxyl groupsvfor each epoxy group present in said diepoxide. I

8 ing at a temperature of 100C. to 200 C. (l) the bis-epoxy ether which has the formula I CH2 C CH: with (2) pentaerythrityl tetraacid maleate phthalate in an amount which provides 0.? to 2.0 carboxyl groups for each epoxy group in said bis-epoxy ether.

5. A process for preparing a cross-linked, resinous product which comprises chemically reacting at a temperature of 100 C. to 200 C. (1) the bis-epoxy ether which has the formula with I (2) pentaerythrityl tetraacid. maleate phthalate in an amount which provides 0.7 to 2.0 carboxyl groups for each epoxy group in said bis-epoxy ether.

v 6. A process for preparing a cross-linked, resinous product which comprises chemically reacting at a temperature of 100 C. to 200 C. (1) the bis-epoxy ether which has theformula with (2) pentaerythrityl tetraacid maleate adipate in an amount which provides 0.? to 2.0 carboxyl groups for each epoxy group in said bis-epoxy ether.

7. A process for preparing a cross-linked, resinous product which comprises chemically reacting at a temperature of 100 C. to 200 C. (1) the bis-epoxy ether'which has the formula 3. A process for preparing a cross-linked. resinous product which comprises chemically reacting at a temperature of 100 C. to 200 C. (1) the bis-epoxy ether which has the formula with (2) pentaerythrityl tetraacid maleate phthalate in an amount which provides 0.? to 2.0 carboxylgroups for each epoxy group in said bis-epoxy ether. 1

4. A process for preparing a cross-linked, res-' amount which provides 0.7 to 2.0 carboxyl groups for each epoxy group in said bis-epoxy ether.

8. A resinouscomposition of matter as preparedby claim 1. v

9,,A resinous composition of matter as prepared by claim 3. lfl A resinous composition of matter as preinous product which comprises chemically reactpared by claim 4;

9 11. A resin us c p ti o a r as p and (2) pentaerythrityl tetraacid maleate pared by claim 5. phthalate in an amount which provides 07 to 2.0

12. A resinous composition of matter as precarboxyl groups for each epoxy group in said hispared by claim 6. epoxy ether.

13. A resinous composition of matter as pre- 5 17. A molding composition containing (1) the pared by claim 7. bis-epoxy ether which has the formula 14. A molding composition containing (1) a diepoxide of a glycol bis-exo-dihydrodicyclopen- CH CH tadienyl ether which has the formula g 0H 0H 0 CH2 CH2 0 on-o CH: 026 OHC on /CH l OHO CaHa-O+CH t on on at l i I I \04 o H E CHOROCH I OH CH and (2) pentaerythrityl tetraacid maleate phthalate in an amount which provides 0.7 to 2.0 in which R is a member of the class consisting of carboxyl groups for each epoxy group in said (a) alkylene groups containing 1 to 12 carbon bis-epoxy ether.

atoms and (1)) groups of the general formula 18. A molding composition containing (1) -(R'O)XR' in which R is an alkylene group the bis-epoxy ether which has the formula 0 CH on on-cf o111 o 2 L\OH-'OH 0 I CH2 (L H2 Po \CH-CH I cH-oc2mo-'oz11io H l CH on c= o o oH,

, of 2 to 4 carbon atoms and a: is an integer havand (2) pentaerythrityl tetraacid maleate adiing a value of 1 to 8 inclusive, and (2) a polypate in an amount which provides 0.? to 2.0 carcarboxylic acid containing 3 to 5 carboxyl groups boxyl groups for each epoxy group in said bisfrom the class consisting of citric, tricarballylic, epoxy ether.

hemimellitic, trimellitic, and pyromellitic' acids 19. A molding composition containing (1) the I and the half-ester-acids of a polyhydric alcohol bis-epoxy ether which has the formula O/L l H: l

from the class consisting of glycerol, pentaerythr mm, dipentaerythritol, mannitol, and sorbitol gg g s ig gigg g gg f tg gigg fi and at least one acid from the class consisting of rou s to e h phthalic, maleic, succinic, glutaric, adipio, sug p r ac epoxy group m Sam ms epoxy beric azaleic and sebacic acids the amount of ether' said polycarboxylic acid being that which pro- JOSEPH KOROLY vides 0.7 to 2.0 carboxyl groups for each epoxy 'REFERENCES CITED group present in said diepoxide.

15. A molding composition containing (1 t The following references are of record in the bisepoxy ether which has the formula me of thls patent:

CH\ CH oH-c I OH: l oH-o11 0 cm s H,

l i a 05 H\ H-O-CrHr-O-CzHr-O- H\ on 0H, 1 CH: and (2) pentaerythrityl tetraacid maleate phthal- UNITED STATES PATENTS ate in an amount which provides 0.7 to 2.0 Number carboxyl groups for each epoxy roup in said 2,527,806 gg i i i 2 fg it 2,541,670 Segall et a1. Feb. 13: 1951 cumming (1) the 2,543,419 Niederhauser Feb.27, 1951 bis-epoxy ether which has the formula OH on C I OH: 

1. A PROCESS FOR PREPARING CROSS-LINKED, RESINOUS PRODUCTS WHICH COMPRISES REACTING AT A TEMPERATURE OF 50* C. TO 250* C. (1) A DIEPOXIDE OF A GLYCOL BIS-EXO-DIHYDRODICYCLOPENTADIENYL ETHER WHICH HAS THE FORMULA 